Assisted reproductive technologies have come a long way since the world's first 'test tube' baby was born in 1978. Not only have techniques been refined, but the science behind selecting the most viable embryos has advanced in recent years, reducing the number of high-order multiple births and improving overall success rates.

Preimplantation genetic testing (PGT) helps clinicians select an embryo that has the highest opportunity for becoming a healthy baby. The technology, which is utilized by Nashville in-vitro fertilization lab Ovation Fertility™, increases the rate of live births resulting from IVF.

Dr. George A. Hill

"About half of all human embryos are chromosomally abnormal," said George A. Hill, MD, medical director for Ovation Fertility and co-founder of Nashville Fertility Center. "Human reproduction is a very inefficient process," he added.

Double board certified in Obstetrics and Gynecology and Reproductive Endocrinology and Infertility, Hill explained embryos used to be selected by a visual pass/fail test based on embryo morphology - an evaluation of the shape, progression of growth and degree of fragmentation within an embryo.

"We used to have to judge the embryo based entirely on its appearance under the microscope at the time the embryo was being transferred back into the uterus," Hill explained. "We now realize that the embryo that looks best under the microscope may not be the most likely embryo to turn into a healthy baby."

Visually picking a 'beautiful' embryo was also a subjective exercise, as different embryologists could have varying opinions as to which embryo was most viable. To maximize pregnancy chances, several embryos were implanted in the hope that one would take. With PGT accuracy rate in excess of 95 percent, Hill said fertility specialists using the technology are now able to transfer fewer embryos. "You begin to reduce the number of multiple births if you do that," he added. "We're doing many more single embryo transfers than we used to. Our goal is one healthy baby at a time."

Although PGT doesn't guarantee a live birth, Hill said it does increase the likelihood far beyond what was historically possible.

"If you look at pregnancy rates of those who undergo comprehensive chromosomal screening, those pregnancy rates get up into the 60-70 percent range or even higher, whereas the national average across the board for IVF is about 35-40 percent, depending on age," said Hill. He added, "We're doing next-generation sequencing, which is the most accurate testing that we can do right now on the embryo."

While the advanced technology adds some expense on the front end, Hill said it's more cost efficient over the entire fertility process. With the testing, fewer embryos have to be transferred and more viable embryos can be held back for later pregnancies without additional IVF cycles.

Perhaps the greatest savings ... both in terms of hard cost and emotional toll ... is giving birth to one or two healthy babies. "If you look at an autosomal recessive disease like cystic fibrosis, and both parents are carriers, they have a one out of four chance of having a baby with the disease," pointed out Hill. With PGT, clinicians can identify and avoid transferring an embryo that has the disease. Fewer implantations also reduces the risk of high-order multiples, who are much more likely to be premature and therefore require longer hospitalization and who potentially face lifelong health issues.

Although the physicians of Nashville Fertility Center have utilized genetic testing for a number of years, Hill said it wasn't to the extent or capabilities of what they could now do as part of Ovation Fertility, a consortium of IVF labs. "The labs were separate, but we merged with several others as part of Ovation Fertility so we're a big group of labs that are now collaborating," Hill said of the change that occurred in June 2015. Currently, Ovation Fertility has labs in Austin, Las Vegas, Nashville, and Newport Beach, Calif., with plans to add more.

Bringing everyone together, he said, has exposed the Nashville team to different viewpoints and geographical variances in processes. "When everyone is in the same room, you look at what you are doing differently and how this can improve your program. I don't think we realized how big that would be."

Hill continued, "The biggest benefit that has come out of it is the collaboration with labs across the country and bringing best practices into our lab to try to improve the chance of everyone's success."

He added, "I think where you are going to see the field go in the next five to 10 years is advancement of the genetic testing that leads to improvement in pregnancy rates as we move toward that goal of one healthy baby at a time."